Rotated DFT-Spread OFDM for Low-PAPR Transmissions

Cho, Li; Kuo, Yu-Ming; Hsu, Chau-Yun

doi:10.1109/icomis.2018.8645037

Cited by 3 publications

(3 citation statements)

References 4 publications

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“…

β = 7 / 32

[9 ]). For simplicity and without loss of generality, for a given M , the modified spacing factor is defined as

β^{normal′} = ℓ / M

to satisfy condition 1 ( M is absolutely divisible by M ), where

ℓ = falsefalse⌊ M β + \frac{1}{2} falsefalse⌋

to satisfy condition 2 (rounding the number to the nearest integer). Then, by exploiting the structure of the R‐DFT‐s‐OFDM [8 ], transform‐precoded symbol vector

S

in (1 ) can be redesigned as

S = {bold-italicR}_{F} ()(, ℓ) {bold-italicW}_{M} s,

where

{[R_{F} (ℓ)]}_{()(, i, j)} ≜ δ_{()(, ()(, i + ℓ) \mod M, j)}

is the

M \times M

frequency‐domain rotation matrix,

δ_{()(, i, j)}

is the Kronecker delta symbol and mod is the modulo operator. Moreover, the comparison of (1 ) and (6 ) shows that the process of improved RM is transferred from the time domain to the frequency domain and is simplified as only an element rotation after DFT (see Fig.…”

Section: Proposed Schemementioning

confidence: 99%

“…The

π / 2

‐BPSK provides an improved statistical performance of PAPR without degrading the bit error rate (BER) performance; however, the rotation angle of the minimal PAPR for rotated BPSK may not exactly locate at

π / 2

[8, 9 ]. In [9, Table I], the authors comprehensively studied the optimal RM angle for different spectrum shaping (SS) cases; however, they only considered the worst‐case PAPRs and did not reveal the problem of unstable PAPR performances with different DFT spacings.…”

Section: Introductionmentioning

confidence: 99%

“…In this Letter, we analysed the PAPR impact of RM‐based BPSK on DFT‐s‐OFDM with different DFT spacings and propose a novel scheme to stably retain the minimised PAPR performances based on the solid extension of rotated DFT‐s‐OFDM (R‐DFT‐s‐OFDM) [8 ]. The proposed scheme only adds an extra rotation for the DFT sequence and, therefore, eases its deployment on the RM‐only system, which is currently standardised in LTE/NR.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Rotated DFT‐s‐OFDM for transmitting PAPR‐minimised BPSK symbols

2020

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The third generation partnership project has recommended π /2‐binary phase‐shift keying (BPSK) in discrete‐Fourier‐transform‐spread orthogonal frequency division multiplexing (DFT‐s‐OFDM) for low peak‐to‐average power ratio (PAPR) uplink transmission. Recently, the rotation angle of 7π /6 for rotated BPSK has been proposed by J. Kim et al. to achieve optimal PAPR performance. However, the authors discovered that this angle might negate the contribution to PAPR reduction in most number of allocated subcarriers owing to the discrete‐Fourier‐transform (DFT) boundary‐matching problem. To solve this issue, they propose a novel scheme to fine‐tune the rotation angle to approximately 7π /6 in a manner compatible with the long‐term evolution/new radio specification, while ensuring that the data phase matches the periodicity. Simulations show that the proposed scheme can stably improve the PAPR by ∼0.2 dB compared to π /2‐BPSK for any DFT spacing, thereby benefiting user equipment by providing better power efficiency and wider signal coverage without additional computational complexity.

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“…

β = 7 / 32

[9 ]). For simplicity and without loss of generality, for a given M , the modified spacing factor is defined as

β^{normal′} = ℓ / M

to satisfy condition 1 ( M is absolutely divisible by M ), where

ℓ = falsefalse⌊ M β + \frac{1}{2} falsefalse⌋

to satisfy condition 2 (rounding the number to the nearest integer). Then, by exploiting the structure of the R‐DFT‐s‐OFDM [8 ], transform‐precoded symbol vector